True to its name, the Bar None ranch offers a haven to a pair of drifters: an 11-year-old orphan, Roy, ``rescued'' from a foster home, and his loyal, hot-headed half-brother, Joe Dilly. Joe has an intuitive gift for handling horses, but his hair-trigger temper has already led to a barn-burning that Roy knows wasn't an accident. Roy, a born rider, is given a quartermile runner, Lady Luck, to train for a race. With an old-fashioned fever remedy, Joe saves Lady Luck's life after a cougar attack, but Joe can't cure his own fever. Triggered by mischief against Roy, Joe's vengeful nature is unleashed, with tragic consequences. Crisply eventful, pungent in its descriptions, crackling with action, Philbrick (Freak the Mighty, 1993) has created a real dilly of a novel. (Fiction. 9-13)